In semiconductor technology, an integrated circuit pattern can be defined on a substrate using a photolithography process. Dual damascene processes are utilized to form multilayer copper interconnections including vertical interconnection vias/contacts and horizontal interconnection metal lines. During a dual damascene process, a plug filling material is employed to fill in the vias (or contacts) and the material is then polished back. However, the vias (or contacts) are defined by a different lithography process and may cause misalignments between the underlying metal lines and the vias. Especially, when the semiconductor technologies move forward to advanced technology nodes with smaller feature sizes, such as 20 nm, 16 nm or less, the misalignments have less tolerance and may cause short, opening or other issues.
Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
Transistors are circuit components or elements that are often formed on semiconductor devices. Many transistors may be formed on a semiconductor device in addition to capacitors, inductors, resistors, diodes, conductive lines, or other elements, depending on the circuit design. A field effect transistor (FET) is one type of transistor. Generally, a transistor includes a gate stack formed between source and drain regions. The source and drain regions may include a doped region of a substrate and may exhibit a doping profile suitable for a particular application. The gate stack is positioned over the channel region and may include a gate dielectric interposed between a gate electrode and the channel region in the substrate. In some structures, other materials are proposed to be used in the gate stack. However, these materials provide advantages of the device performance on one side and introduce new problems, such as hysteresis issue, on another side.
Therefore, the present disclosure provides a semiconductor structure and a method making the same to address the above issues.